1. Field of the Invention
The present invention generally relates to video encoders. More specifically, the present invention provides multipass encoding of a video sequence without encoding the entire video sequence on each pass.
2. Background Art
Highly efficient video compression can be achieved by multipass encoding. With multipass encoding, a video sequence is encoded several times and each encoding pass uses the results of the preceding pass to adjust coding parameters to optimize, for example, average bit rate and/or decoder buffer fullness. Overall, the mulitpass encoding process is a trial and error process: select initial coding parameters, code the video sequence, examine the results to determine if performance requirements are met and recode as necessary using adjusted coding parameters for each subsequent iteration.
For long sequences of digital video, however, coding the entire video sequence several times is inefficient and greatly increases the time required to generate an efficiently compressed sequence. Accordingly, what is needed is an encoder capable of generating a compressed video sequence by multipass encoding without encoding the entire video sequence on each pass.